health « blog about science

Production of universal red blood cells

April 11, 2007 — jmgs

A team of researchers has found a feaseble way of producing universal red blood cells. This is a very important step towards the goal of improving the blood supply while enhancing the safety of clinical transfusions.

In the new study, the researchers found two bacterial glycosidase gene families with enzymes that efficiently remove A and B antigens from red blood cells (RBCs).

The reference to the the work is the following:

“Bacterial glycosidases for the production of universal red blood cells.” Qiyong P Liu, Gerlind Sulzenbacher, Huaiping Yuan, Eric P Bennett, Greg Pietz, Kristen Saunders, Jean Spence, Edward Nudelman, Steven B Levery, Thayer White, John M Neveu, William S Lane, Yves Bourne, Martin L Olsson, Bernard Henrissat & Henrik Clausen. Nature Biotechnology Published online: 1 April 2007 doi:10.1038/nbt1298

abstract in: http://www.nature.com/nbt/journal/v25/n4/abs/nbt1298.html

Diets damage health, shows biggest ever study.

April 10, 2007 — pgomes

The world’s largest study of weight loss has shown that diets do not work for the vast majority of slimmers and may even put lives at risk. More than two-thirds pile the pounds straight back on, raising the danger of heart attack, stroke and diabetes.

Indeed most dieters end up heavier than they did to start with, the researchers found. They warn this type of yo-yo behaviour is linked to a host of health problems. And they say the strain that repeated weight loss and gain places on the body means most people would have been better off not dieting at all.

The findings follow other research that shows the UK is in the grip of a dieting frenzy, with one in four Britons at any one time trying to lose weight. The average woman is estimated to lose and gain 251/2 stone during her lifetime - putting on 151/2 stone for the ten stone she loses through dieting. Last night, the U.S. scientists behind the latest research - the most thorough and comprehensive analysis of its kind - said that dieting simply does not work.

The University of California researchers analysed the results of more than 30 studies involving thousands of slimmers. Although the overview did not name specific weight loss plans, popular diets in recent years include the low carbohydrate, high protein Atkins diet and the GI diet, which is rich in slow-burning wholegrain carbohydrates. Pooling the results of the various studies clearly showed that while people do lose weight initially, most quickly put all the pounds back on.

In fact, most people end up weighing more than they did to begin with. Researcher Dr Traci Mann said: “You can initially lost 5 to 10 per cent of your weight on any number of diets. “But after this honeymoon period, the weight comes back. We found that the majority of people regained all the weight, plus more. Sustained weight loss was found only in a small minority of participants, while complete weight regain was found in the majority.”

Dr Mann’s research showed that up to two-thirds of dieters put on all the weight they lose - and more - over a four to five-year period. Half of those taking part in one study were more than 11lb heavier five years later, while dieters taking part in another study actually ended up heavier than other volunteers who hadn’t tried to lose weight.

A four-year study into the health of 19,000 men revealed that most of those who put on weight had dieted in the years before the start of the study. Bleak as these figures seem, the true picture could be even worse, as it is thought that most people lie about their weight - and don’t like to tell researchers that their weight has started to creep up again. The analysis, published in the journal American Psychologist, concluded dieters may actually be damaging their health.

Research has shown the repeated rapid weight gain and loss associated with dieting can double the risk of death from heart disease, including heart attacks, and the risk of premature death in general. Such yo-yo weight loss has also been linked to stroke and diabetes and shown to suppress the immune system, making the body more vulnerable to infection.

Dr Mann said: “We decided to dig up and analyse every study that followed people on diets for two to five years. We concluded most of them would have been better off not going on the diet at all. “Their weight would have been pretty much the same, and their bodies would not suffer the wear and tear from losing weight and gaining it all back. “The benefits of dieting are simply too small and the potential harms of dieting are too large for it to be recommended as a safe and effective treatment for obesity.”

The psychologist, who advises would-be slimmers to swap calorie-controlled diets for a balanced diet coupled with regular exercise, added: “Exercise may well be the key factor leading to sustained weight loss. Studies consistently find that people who report the most exercise also have the most weight loss.” The finding comes as Britain fights a rising tide of obesity. A growing reliance on fast food and time-saving technology has led to the UK developing the worst weight problem in Europe, with almost a quarter of adults classed as obese. British experts said that fad diets do not work and that the key to maintaining a healthy weight is making gradual, long-term changes.

Dr Beckie Lang, of the Association for the Study of Obesity, said: “Maintaining a healthy weight isn’t about going on a diet and coming off a diet when you reach your target weight. It is about adopting skills that change your eating habits for life.”

http://www.cfsan.fda.gov/~comm/tds-toc.html

http://www.rush.edu/rumc/page-1099611527922.html

Posted in Science, health. No Comments »

What are dioxins?

March 29, 2007 — jmgs

Taking the hint from a previous post by pgomes (The Egg Report), I thought it would be interesting to post something more about dioxins. So here it is.

from wikipedia: “Dioxin is the popular name for the family of halogenated organic compounds, the most common consisting of polychlorinated dibenzo furans (PCDFs) and polychlorinated dibenzodioxins (PCDDs). PCDD/PCDFs (PCDD/Fs)” . (see figure)

Dioxins bioaccumulate in fatty tissues, which means that even small exposures may eventually reach dangerous levels since these molecules present carcinogenic properties.

To find out more about this subjects click the following links:

http://en.wikipedia.org/wiki/Dioxin

http://www.niehs.nih.gov/oc/factsheets/dioxin.htm

http://ec.europa.eu/environment/dioxin/index.htm

http://www.ejnet.org/dioxin/

Posted in Chemistry, Science, health. No Comments »

Emotions, moral dilemmas and brain structure

March 29, 2007 — jmgs

In an article published in February in Nature, a group of researchers presents a study where it is shown that lesions of a certain part of the brain, the ventromedial prefrontal cortex, alters the normal judgements of right and wrong for a selective set of moral dilemmas. Being that this part of the brain is related to emotions, it is apparent that emotions and moral judgement are related.

You can find the article in “Damage to the prefrontal cortex increases utilitarian moral judgement (Michael Koenigs, Liane Young, Ralph Adolphs, Daniel Tranel, Fiery Cushman, Marc Hauser, Antonio Damasio)

Posted in Science, health, neurosciences. 2 Comments »

The Egg Report.

March 22, 2007 — pgomes

Contamination of chicken eggs from 17 countries by dioxins, PCBs and hexachlorobenzene:

” A study of free-range chicken eggs collected near waste incinerators, cement kilns, the metallurgical industry, waste dumps, and chemical production facilities involving chlorine found evidence of high levels of dioxin and PCB contamination. Seventy percent of the samples exceeded the European Union (EU) limit for dioxins in eggs. Sixty percent of them also exceeded proposed EU limits for PCBs in eggs. Three egg samples reported in this study contain some of the highest dioxin levels ever measured in chicken eggs. To our knowledge, this study represents the first data about these substances in chicken eggs for Belarus, Bulgaria, Egypt, India, Mexico, Kenya, Mozambique, Philippines Senegal, Tanzania, Turkey, and Uruguay.”

source:http://ipen.ecn.cz/index.php?z=&l=en&k=enabling&r=viewtxt&id=111&id_rubriky=12

Posted in Science, health. 1 Comment »

Chemistry and Sport. Not an easy relation. (By Paulo J. S. Gomes)

March 19, 2007 — pgomes

Every day, we interact with a host of synthetic and natural chemicals whose importance shows up in our favourite sports. Advances in the chemical and materials sciences, in particular, have had a dramatic impact on sporting events. For example, the use of polymeric materials in car bodies results in lighter and faster vehicles in auto racing, and carbon composite materials help to protect the drivers in the cockpits of open wheel race cars. In tennis, skiing, bowling, and fishing, polymers, composites, and other advanced materials are used routinely to produce high-performance equipment.

Despite the great advantage from use of the knowledge give by Chemistry in sport, this relation it’s not always morally correct. All of us as already hear to talk about doping.

Pierre de Coubertin, founder of the modern Olympic games, was one of the first to point out the necessity of protecting sport from the dangers threatening it as an institution. In 1923, in a speech delivered in Rome, he denounced “the intrusion of politics into sports, the increasingly venal attitude towards championship, the excessive worshipping of sport, which leads to a belief in the wrong values, chauvinism, brutality, overworking, overtraining, and doping”.

The recent doping scandal of the last Tour de France cycling competition drew the attention of the media to practices which, until then, had remained covert. This media coverage has increased public awareness of this phenomenon. Indeed, due to their scope and sophistication, doping practices are a threat to more than just the world of sport. Though first considered to be no more than a cheating problem, the doping issue has reached such proportions that it now concerns society as a whole. As the stakes involved in sport grow higher and the phenomenon more widespread, the moral values attached to sport are increasingly called into question and the health of athletes increasingly at risk.

History, confirms that the use of chemical shortcuts to success in sports is an age-old problem. Recorded drug use goes back more than two thousand years. The Roman gladiators, who ate mushrooms and seeds that affected the mind, also drank herbal stimulants to dull their fear and to make them stronger and more able.

As early as the late 19^th century cyclists were using substances like caffeine, cocaine and ether-coated sugar cubes to improve performance, reduce pain and delay fatigue. Nazi Germany athletes were rumoured to use the first rudimentary testosterone preparations in the 1936 Summer Olympics.

Nowadays an Italian judge is investigating the suspicious death of 70 football stars amid fears that drugs their clubs gave them may have triggered their fatal illnesses. Raffaele Guariniello, a magistrate in Turin, is probing the unusually high incidence of cancer, leukaemia and a rare disease of the nervous system among players who have appeared for top clubs such as Juventus, Roma and Milan. ‘Out of 400 deaths since 1960, we are investigating 70 suspicious ones,’ said Guariniello, who is researching the records of 24,000 professional Italian players between 1960 and 1996. ‘Many more players are dying of these diseases than members of the public.’

Athletes use androgenic–anabolic steroids to increase strength, lean body mass, and, in some cases, to improve physical appearance. To minimize the risk of developing tolerance to any particular agent, androgenic–anabolic steroids are taken as a cocktail of different agents taken at one time. In English-speaking countries, the process is called “stacking.” Perhaps the most worrisome aspect of this problem is its universality. Abuse of these agents is said to be widespread amongst both amateur and professional athletes. According to the International Olympic Committee, steroids account for more than 50% of positive doping cases. Although the topic is still being debated, and most of the evidence is anecdotal, a consensus is beginning to emerge that chronic androgenic–anabolic steroids abuse may be associated with an increased risk of sudden cardiac death, myocardial infarction, altered serum lipoproteins, and cardiac hypertrophy.